An Organic Light-Emitting Diode (OLED) display is one of focuses in the research field of flat panel displays, and since the OLED display has low power consumption, a low production cost, self-emission, a wide angle of view, a high response speed, and other advantages over a liquid crystal display, the OLED display has come to take the place of the traditional Liquid Crystal Display (LCD) in the field of mobile phones, Personal Digital Assistants (PDAs), digital cameras, and other flat panel displays. The design of a pixel circuit is a core technology in the OLED display, and a research thereon is of significance.